Nato yesterday accused Russia of ramping up tensions with its neighbour Georgia and said Moscow's rapid build-up of troops in the breakaway republic of Abkhazia threatened Georgia's territorial integrity.

The alliance called on Russia and Georgia to resolve their differences over Abkhazia and South Ossetia, Georgia's two rebel republics, amid ominous signs of a looming military confrontation.

Nato's secretary general, Jaap de Hoop Scheffer, also derided Russian claims that a Nato jet may have shot down a Georgian drone last week over Abkhazia. Georgia says a Russian MiG-29 shot it down. Russia's Nato envoy had suggested the alliance was responsible.

"The secretary general had said he'd eat his tie if it turned out that a Nato Mig-29 had magically appeared in Abkhazia and shot down a Georgian drone," Nato spokesman James Appathurai said. He added: "There is no danger of the secretary general getting ingestion."

"The steps taken (by Russia) ... and the rhetoric that has been used concerning the threat of force have undermined Georgia's territorial integrity," he declared. On Tuesday Russia accused Georgia of plotting to attack Abkhazia, and announced that it was deploying additional troops and military equipment in the region. Around 1,000 Russian peacekeepers are already stationed in Abkhazia, which broke away from Georgia following a 1992-3 war.

The move came after Russia's president, Vladimir Putin, this month recognised Abkhazia and South Ossetia as legal entities - prompting a furious response from Tbilisi, which accused Russia of trying to annexe the territories by stealth.

Georgia has denied it has plans to invade Abkhazia, a small and picturesque territory on the sub-tropical eastern coast of the Black Sea. Georgia's special presidential envoy, David Bakradze, has appealed for international solidarity, holding talks yesterday with the EU foreign policy chief Javier Solana.

"Georgia is being pushed to the edge of a precipice. Without credible and concerted reaction, we are confronted by the prospect of a situation similar to that in northern Cyprus or analogous to what occurred in Taiwan," Bakradze said.

He added: "Russia's end goal now appears to be to force Georgia into armed conflict. It would thus strip it of the opportunity to earn Nato membership, while finally annexing Georgia's territories."

Abkhazia's separatist leadership has echoed Russian claims that Georgia is massing forces in the Upper Kodori Valley - a strategic enclave controlled by Georgian forces but inside rebel-held territory. Some 1,500 troops were there, it said.

He added: "I would characterise the situation as tense, but stably tense," Abkhazia's vice-foreign minister, Maxim Gunjia, told the Guardian.

Recent developments are likely to alarm the US and the EU. Both have expressed support for Georgia and its territorial integrity.

Russia has lifted economic sanctions against Abkhazia and given passports to most of its citizens. On Tuesday Russia's foreign minister Sergei Lavrov said that Moscow had a right to defend them if they came under Georgian attack. Last night Abkhazia's foreign minister, Sergei Shamba, confirmed Russia had boosted its troop contingent from 2,000 to 3,000.